FUEL PUMP RELAY WOES

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John Vauden
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Joined: Sun 05 Aug, 2018 6:17 pm
Model you own: w201
Region: New South Wales
Location: Coogee

FUEL PUMP RELAY WOES

Post by John Vauden » Tue 11 Sep, 2018 7:28 pm

Hi All,

Was wondering if you could help me. My fuel pump relay is shot and the car won't go. It isn't the fuel pump because if you give the relay a decent "Tap" car starts and drives like new.

My issue is :

*Relay in my car is a 002 5452105 9 pin relay
*Only ones that seem to be available are 0035452005 10 pin relay (see pictures attached)

Part 0035452005 has an extra pin labeled 87H and the fitting in my car has a solid blank where this pin should go.

Mercedes Benz and a whole host of others say that these parts should be interchangeable and they simply are not in my case!

Any suggestions? As my daily drive is now too unreliable to drive in traffic and I can't seem to source a relay from anywhere. My last hope was a company in the USA who said they had the part but in fact shipped me a useless 0035452005.

I've had plenty of Mercs before and NEVER had an issue like this EVER! Anyone had similar issues and if so what was the fix short of scrapping the car?

Cheers

John

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Tony From West Oz
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Posts: 3222
Joined: Mon 20 Jun, 2005 9:04 pm
Model you own: w202
Location: Bedfordale WA

Re: FUEL PUMP RELAY WOES

Post by Tony From West Oz » Tue 11 Sep, 2018 10:43 pm

You have purchased the relay with the extra pin.
It is supposed to be a compatible replacement with your faulty one, but your relay socket does not have a place for the extra pin to go.
Option 1. Shade-tree mechanic in me says to cut the extra pin off the replacement relay and see if it works in your car - You have the relay but can't try it out ,as it stands.
Getting the seller to take it back and/or replace with one which has the correct number of pins is likely to be impossible / prohibitively expensive. Freight would be the killer even if the seller accepted returns. What have you to lose by modifying the replacement relay? Only a relay that you can't use!

Option 2. Get your faulty relay and have an electronics whiz look at it with a view to repairing it.
It may be a simple dry joint in the soldering.

Option 1 and 2 are not mutually exclusive and may be investigated in any order.

I hope this is of some assistance in your dilemma.
Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (SOLD)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

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Christo C
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Re: FUEL PUMP RELAY WOES

Post by Christo C » Wed 12 Sep, 2018 12:35 pm

>> if you give the relay a decent "Tap" car starts and drives like new.

That’s the clue it is most likely a dry joint in the old relay; less likely is a dodgy socket.
if you want to bring it over I could look at it - I’m in Beaconsfield (aka Alexandria) - but would have to be before Saturday when I go away... ph 0411 850 822

Alternatively just cut the extra pin off the ‘new’ relay.
~Christo
1986 230E W124.023 M102.982 ~290,000km Thistle Green Saloon "Janis"

John Vauden
Posts: 2
Joined: Sun 05 Aug, 2018 6:17 pm
Model you own: w201
Region: New South Wales
Location: Coogee

Re: FUEL PUMP RELAY WOES

Post by John Vauden » Fri 14 Sep, 2018 8:42 am

Hi all,

after careful consideration, I decided to future proof my car by drilling out hole 5 in the picture.
IMG_6245.jpg
Access is horrendous I'm sure to have developed carpal tunnel syndrome as a result! I but I've nearly got the relay home and think a small file from bunnings will do the trick. That's my next purchase!

The best news is that even with the relay sitting 3/4 in the car starts and drives like new!

Thanks to all that responded. Hopes this helps anyone else out there is this issue?
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CraigB
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Location: Hawthorndene (Adelaide)

Re: FUEL PUMP RELAY WOES

Post by CraigB » Fri 14 Sep, 2018 9:05 am

Well done! Threads like this with a problem and a solution are great and can really help people in the future.
Craig Baulderstone
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